Hill sessions help for sure but as you only have 5 weeks left and that would be only one session if your looking at the get you round plan I wouldn't bother.
Everyone is different. A lot of people on here are quite cautions in their advise as injury is a real danger, also most are strong and regular runners.
I think there is a big difference between running a solid and confident 1/2 and just getting round one, say as a charit fund raiser.
What Graham has stated above is good advise but no good to you as you only have 5 weeks.
If you can't run more than 6 mins without walking slow down.
If you have to walk periodically in training then you can always do the same in your race, better to take walk breaks all the way through that crash at 9 miles and have to walk the rest.